Embarrassingly I don’t know how to do that scientifically. I can tell you latency of the storage system which at a very simplistic snapshot is averaging around 2ms. We are not using SSD for metadata but 10K SAS.
From: [email protected] [mailto:[email protected]] On Behalf Of J. Eric Wonderley Sent: 22 March 2017 13:41 To: gpfsug main discussion list <[email protected]> Subject: Re: [gpfsug-discuss] snapshots & tiering in a busy filesystem The filesystem I'm working with has about 100M files and 80Tb of data. What kind of metadata latency do you observe? I did a mmdiag --iohist and filtered out all of the md devices and averaged over reads and writes. I'm seeing ~.28ms on a one off dump. The pure array which we have is 10G iscsi connected and is reporting average .25ms. On Wed, Mar 22, 2017 at 6:47 AM, Sobey, Richard A <[email protected]<mailto:[email protected]>> wrote: We’re also snapshotting 4 times a day. Filesystem isn’t tremendously busy at all but we’re creating snaps for each fileset. [root@cesnode tmp]# mmlssnapshot gpfs | wc -l 6916 From: [email protected]<mailto:[email protected]> [mailto:[email protected]<mailto:[email protected]>] On Behalf Of J. Eric Wonderley Sent: 20 March 2017 14:03 To: gpfsug main discussion list <[email protected]<mailto:[email protected]>> Subject: [gpfsug-discuss] snapshots & tiering in a busy filesystem I found this link and it didn't give me much hope for doing snapshots & backup in a home(busy) filesystem: http://www.spectrumscale.org/pipermail/gpfsug-discuss/2013-February/000200.html I realize this is dated and I wondered if qos etc have made is a tolerable thing to do now. Gpfs I think was barely above v3.5 in mid 2013. _______________________________________________ gpfsug-discuss mailing list gpfsug-discuss at spectrumscale.org<http://spectrumscale.org> http://gpfsug.org/mailman/listinfo/gpfsug-discuss
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